Biomaterials for Water Purification: Dyes, Heavy Metals, and Pharmaceuticals

Abstract

In this chapter, the emphasis is on biowaste materials generally characterized by various functional groups, such as carboxyl, amine, and hydroxyl, that are used for the removal of heavy metals. The chapter discusses chitosan-based polymeric membranes for water purification, where chitosan-containing polymeric nanocomposites are used for water purification systems, as well as for adsorption of Cu(ii) and Zn(ii) ions in water and for biosorption of organic dyes. It is essential that adsorbent membranes used are effective in the removal of toxic metals, heavy metals, drugs, and dyes. For example, phosphate cellulose as biomaterial under different pH conditions can be used for effective removal of the drug ranitidine from water. The use of biowaste as an adsorbent to effectively remove toxic heavy metals, dyes, and drugs is challenging due to their nature with respect to adsorption, recovery, effectiveness, and recyclability. Biowastes obtained from agriculture, in particular, have been utilized as effective biosorbents in the water purification process. Biosorption is effective for removal of heavy metals from waste water compared with conventional methods. However, chitosan-based polymeric materials possess a high adsorption efficiency compared to biowaste materials, for the effective removal of heavy metals, various drugs, dyes, etc. This chapter also focuses on the mechanisms of adsorption of chitosan-based polymeric materials and biowaste products for effective removal of various heavy metals, drugs, and dyes, and their involvement in high adsorption efficiency, stability, and low cost.